David Kierznowski discovered that libcurl, a multi-protocol file transfer
library, when configured to follow URL redirects automatically, does not
question the new target location. As libcurl also supports file:// and
scp:// URLs - depending on the setup - an untrusted server could use that
to expose local files, overwrite local files or even execute arbitrary
code via a malicious URL redirect.

This update introduces a new option called CURLOPT_REDIR_PROTOCOLS which by
default does not include the scp and file protocol handlers.

For the oldstable distribution (etch) this problem has been fixed in
version 7.15.5-1etch2.

For the stable distribution (lenny) this problem has been fixed in
version 7.18.2-8lenny2.

For the unstable distribution (sid) this problem has been fixed in
version 7.18.2-8.1.